The (S)-N-benzylprolinol carbamate (S)-8 is deprotonated by sec-butyllithium with the removal of the pro-R-H and the intermediate lithium compound 10 is trapped by several electrophiles. Complete ul-diastereotopos-differentation is achieved irrespective of the supporting additive [TMEDA, (-)-sparteine, or ether]. For the homologous piperidine derivative rac-9, the substrate-directed diastereoselectivity is less pronounced (~6:1). Thus, an efficient kinetic resolution is observed by means of sec-butyllithium/(-)-sparteine, leading to the preferential consumption of the (+)-(R)-9 with abstraction of the pro-S-H, followed by its substitution by electrophiles. Enantioenriched (-)-(S)-9 remains unchanged.